Date: Wed, 21 Mar 2012 23:56:49 +0000 (GMT) From: andy thomas <andy@time-domain.co.uk> To: freebsd-fs@freebsd.org Subject: ZFS read/write performance slows with time Message-ID: <Pine.GSO.4.64.1203212341010.5175@mail.time-domain.co.uk>
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A server running 64-bit FreeBSD 8.0 boots from a SATA disk and then mounts a ZFS mirror consisting of two SAS disks plus one spare. Immediately after booting, the filesystem is fast and responsive and 'zpool iostat -v tank' reports read and write disk bandwidths of over 22 MB. But over a period of time, this performance begins to deteriorate and after 180 days of uptime this server, which is running mail, samba and webmail servers in 3 separate jails, really struggles especially the IMAP daemon. zpool iostat -v reports a maximum read bandwidth of around 2MB and a write bandwidth of 143 KB maximum. Rebooting the system restores normal performance but the cycle gradually repeats itself. I can't see anything wrong in any log and the system has 12 GB of memory and a 2 Ghz quad-core Xeon CPU so it isn't under-resourced. At boot time ZFS reports its version as being 13 - could the problem be due to a memory leak or some other issue with early versions of ZFS that have since been fixed in later FreeBSD releases? Andyhelp
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